Measles -- Hawaii

Between May 5, and June 29, 1984, 106 cases of measles were
reported on the island of Kauai, Hawaii (Figure 3). All met the
clinical case definition* for measles; 25 cases were serologically
confirmed.** Four distinct generations of illness were identified
10-12 days apart. The second generation (May 17-28) was the
largest,
with 35 (33%) cases. No source was identified. Seven children
(7%)
of the 106 patients were hospitalized secondary to measles. Three
were hospitalized for diarrhea and dehydration, and four, for
evaluation.

The single largest group of cases, 52 (49%), occurred among
children under 5 years of age, including 36 (34%) under 16 months
of
age (Table 4). Persons 15-19 years of age were the next largest
group, accounting for 27 (25%) cases. Forty-five (42%) of the
cases
occurred among school-aged children (5-19 years). Although more
than
two-thirds of the first generation occurred among school-aged
children
(15/22), the second generation occurred mainly in preschool-aged
children 0-4 years of age (25/35). Further investigation revealed
that 16 (46%) of the 35 second-generation cases were among infants
15
months of age or younger,*** compared to two (9%) of 22 cases in
the
first generation. High school students accounted for 34 (75%) of
the
school-aged patients. Seven additional cases occurred at four
elementary schools.

Of the 106 cases, 48 (45%) were considered preventable****
(Table
5). Thirty-two of these patients had no record of measles
vaccination
or prior physician-diagnosed natural disease, and 16 had been
vaccinated at under 12 months of age. Thirty-six of the 58
nonpreventable cases***** (62%) occurred among children 15 months
of
age or younger, most of whom were too young for routine
vaccination.
Eighteen (31%) of the nonpreventable cases had been immunized
appropriately.****** The remaining four measles patients were 28
years of age or older--too old for routine vaccination. Of the 45
school-aged patients, 16 (35%) were vaccinated at 12 months of age
or
under; 12 (27%) were unvaccinated. Thus, non-immune schoolchildren
accounted for 58% (28/48) of all preventable measles cases.

Sixteen persons who subsequently developed measles had visited
a
doctor's office in May and June at the same time a patient with
known
or suspected measles was being seen in the office; one additional
person was seen within 45 minutes after a patient with known
measles
left the office. All such visits occurred 8-14 days before onset
of
rash. Sixteen of the cases were in children; one was in a parent
of
one of these children. Mothers of four recalled face-to-face
contact
in the waiting room between their children and another child with
rash. In 12 cases, for which exact times were available, the
exposed
person had been in the office with the measles patient for 20-90
minutes. No other possible sources of measles exposure were
identified for these 17 cases. Interviews with parents revealed
that,
of the 16 children involved in office transmission, two were in the
office primarily for measles-mumps-rubella vaccine, and four, for
routine examination; four accompanied an ill relative; and seven
were
ill themselves. Transmission in physicians' offices was most
important in infecting young preschool-aged children. Such
transmission accounted for 36% of cases among children 15 months of
age and under and 31% of cases among children under 5 years of age.

Interviews with office staff revealed that procedures for
isolating sick children from well children in the office were not
well
implemented. In many cases, parents brought in their children
complaining of high fever and rash without appointments and either
had
to wait in or pass through a common waiting room.

On June 6, because of increasing evidence that up to one-third
of
all measles cases were occurring among children under 15 months of
age, measles vaccination recommendations were extended to children
as
young as 6 months of age for the duration of the outbreak. On June
7,
to limit measles transmission in private offices, the Hawaii
Department of Health recommended that health professionals: (1)
screen patients requesting appointments by asking if symptoms of
rash
and fever were present. If possible, such patients should then be
seen in separate facilities or at the end of the day after all
other
patients had left; (2) keep suspected measles patients in
respiratory
isolation in separate rooms with face masks to limit spread of the
virus; they should be given priority and seen as soon as possible.

Although measles cases continued to be reported in June and
July,
the last case of suspected intraoffice transmission occurred on
June
7. With the implementation of isolation precautions and continued
vaccination of susceptible children and adults, reports of measles
cases began to decline after the third generation (Figure 3).

To define other populations at risk for disease, an island-wide
school and day-care center health record review was done. A
student
was considered susceptible to or at high risk for measles if there
was
no record of receipt of live measles vaccine on or after the first
birthday and no record of physician-diagnosed measles. Using this
definition, 47% (1,864/3,986) of high school students and 22%
(1,109/5,100) of elementary, private, and parochial school students
were considered susceptible. Those students were asked to provide
proof of previous adequate vaccination or be vaccinated in
school-based clinics, held in all three high schools before
graduation
and end of school or in public clinics. Over 1,000 students were
vaccinated at the high school clinics. Approximately 400 persons
were
vaccinated in 13 public clinics held between June 7 and June 15 for
the general public and elementary and private schools.
Reported by H Michioka, SMD Terrell-Perica, P Tokita, M Tsuchiya, T
Inouye, Kauai District Health Office, K Corrigan, A Hendersen, CM
Ibara, G Kobayashi, R Salcido, C Wakida, A Liang, MD, State
Epidemiologist, Hawaii State Dept of Health; Div of Field Svcs,
Epidemiology Program Office, Div of Immunization, Center for
Prevention Svcs, CDC.

Editorial Note

Editorial Note: Over the last 5 years, Hawaii has made significant
progress towards measles elimination. The last major cluster of
measles cases occurred in 1979, when 68 cases were reported. Fewer
than seven cases had been reported annually in Hawaii since 1980.
The
present outbreak confirms that measles can occur in populations
essentially free of disease for long periods. The source of this
outbreak was not determined.

Hawaii's immunization law, enacted in 1974, covers only new
school
enterers and has been vigorously enforced only since about 1976.
In
this outbreak, susceptible schoolchildren made up 62% (28/45) of
all
school-aged measles patients. The predominance of high school
students among the school-aged patients may, in part, reflect a
higher
susceptibility rate among the age group that was too old to be
affected by the law. Only the year of vaccination was required for
the school record. Considerable numbers of susceptibles were
identified, because many students had records of vaccination in the
year of, or the year following, birth, making determination of who
was
vaccinated on or after the first birthday impossible. Vigorous
enforcement of comprehensive school laws covering all students from
kindergarten through grade 12 has been demonstrated to be the most
effective means of reducing measles incidence rates (1).

This outbreak is also important because of the large number of
preschool-aged children who acquired measles. Of the 52
preschool-aged children with measles, 69% were under 16 months of
age
and their cases, therefore, were nonpreventable. However, 15
children
in the preschool-aged group simply had not been vaccinated, and
their
measles could have been prevented (Table 5).

This investigation suggests that transmission in physicians'
offices played a major role in perpetuating the outbreak,
particularly
among children too young for routine vaccination. Intraoffice
transmission can occur both when droplet nuclei are aerosolized by
coughing children and by direct physical contact between children.
Measles outbreaks in medical offices, airports, and other settings
have been propagated by susceptible persons inhaling
measles-containing droplet nuclei left by infected persons (2-4).
Transmission in medical offices has been documented to have
occurred
up to 75 minutes after an infectious person has left the office
(5).
The opportunity for intraoffice transmission by both direct contact
and airborne routes was present on Kauai.

In situations where exposure has already occurred, susceptible
persons who had face-to-face contact with a measles patient may
benefit from immune globulin prophylaxis, if it is given within 6
days
of exposure. Measles vaccination may provide protection if it is
given within 72 hours of exposure. Prophylaxis is not generally
offered to persons who have not had face-to-face contact but were
in
the office with the patient or arrived after the patient departed.
The rarity of reports of transmission in doctors' offices suggests
that airborne transmission is uncommon. Denominator data that
would
have defined the actual risk of measles for patients in a
physician's
office in this outbreak are lacking. However, should future
outbreaks

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